Missile guidance system



y 21, 1964 M. F. DAVIS ETAL MISSILE summers SYSTEM Filed Feb. 16, 1953 zmwwwau INVENTORS MARION E DAVIS ALBERT L. HEDRICH flwm ATTORNEYS United States Patent 3,141,635 MISSILE GUIDANCE SYSTEM Marion F. Davis, 323 Plymouth St., and Albert L. Hedrieh, 8705 Leonard Drive, both of Silver Spring,

Filed Feb. 16, 1953, Ser. No. 337,254 12 Claims. (Cl. 24414) (Granted under Title 35, US. Code (1952.), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to guidance systems for gun-launched non-powered rotating missiles having a guidance charge and more particularly to apparatus for transmitting information indicative of the rotative orientation of such missiles to a command station. The missile employed in the present invention is of the type disclosed in the co-pending application of Harold J. Plumley for Method and Apparatus for Steering a Gun-Launched Missile, Serial No. 131,441, filed December 6, 1949, the missile being of a type which is launched from a gun by an explosive propelling charge and has contained therein an explosive charge under the control of a proximity fuze mounted in the nose of the missile and operable to fire the charge when the missile reaches a predetermined proximity with respect to a target. A steering charge is mounted in the missile and is arranged to expend the explosive force thereof perpendicular to the line of trajectory of the missile to change the angle of trajectory thereof by approximately and radiating outwardly from the initial trajectory at a selected angle on reception of a signal from a command station preferably positioned adjacent the propelling gun.

In order to increase the effective target area of the missile, the missile is caused to rotate at approximately revolutions per second by a plurality of canted fins attached adjacent the trailing end thereof. In this manner the steering charge may be fired at any selected point during each complete revolution of the missile.

In order to provide information indicative of the instantaneous rotational orientation of the missile during the flight thereof at the command station, the missile casing is formed with a radar mirror in the trailing end thereof, the mirror being tilted at a suitable angle in which the normal of the mirror is not coincident to the longitudinal axis of the missile. It will thus be seen that when a microwave radar beam is directed toward the missile in flight from the command station, the beam is reflected or diffracted asymmetrically to provide a maximum signal at the command station when the beam is reflected downwardly by the mirror with respect to the rotational axis of the missile and to provide a minimum signal when the beam is reflected upwardly with respect to the rotational axis of the missile. Thus, a signal is reflected toward the command station by the mirror which reaches a maximum once during each rotation of the missile and which may be followed by a tracker.

It is thus a function of the present invention to provide information at the command station of the instantaneous rotational orientation together with the range, elevation, and azimuth of the missile during the flight thereof.

An object of the present invention is to provide a new and improved apparatus and system for determining the instantaneous rotational orientation of a rotating missile during the flight thereof.

Another object is to provide a new and improved radar mirror for a rotating missile which reflects a radar beam transmitted by a command station in such manner as to provide a reflected signal, receivable at the command station, which varies in intensity during each revolution of the missile.

Still another object is to provide a new and improved apparatus and system for a rotating missile employing a canted rotating mirror for reflecting a radar beam to a command station to provide information relating to rotational orientation and distance along the trajectory of the missile.

A further object is to provide a rotating missile which is readily adapted to missile traflic control when a plurality of missiles are in flight at the same time.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

FIGURE 1 of the drawing indicates, in schematic diagram, at system in accordance with the present invention and employing a canted radar mirror in the tail portion of a rotating missile.

FIGURE 2 shows the radar beam reflected from the canted mirror.

Referring more particularly to the drawing in which like characters indicate like parts throughout the several views A indicates a non-powered rotating missile which is travelling along a trajecory C, the longitudinal axis of the missile A being substantially tangent to the trajectory. Missile A is preferably propelled by a gun (not shown) located adjacent a command station D.

Missile A comprises a metallic casing 10 having a nose portion 11 and a canted tail portion forming a radar mirror or reflector 12, as will be hereinafter more fully described. Slightly canted fins 13 are attached adjacent the tail portion and are arranged, for example, to impart rotation to the missile during its flight. For example, the missile may rotate at a rate which decreases from 20 revolutions per second to 10 revolutions per second during flight over the useful portion of the trajectory of the missile.

A plurality of steering charge ports 14 are formed in one side of missile casing 10 and contain charges (not shown) arranged to be fired simultaneously upon reception of a signal from a command transmitter CT of command station D.

Command station D comprises a radar transmitter and receiver RA, a rotational tracker RT, a fire control system PC, and the command transmitter CT. Radar or microwave transmitter and receiver RA has associated therewith an antenna 15 which is employed to transmit a microwave beam M in the direction of missile A during the flight thereof.

As shown in FIG. 2 of the drawings, the intensity of the signal reflected by mirror 12 is governed by the angle of reflection of the signal passing through the reflection pattern, the signal reaching maximum intensity when reflected along a line perpendicular to the face of the mirror 12, the intensity being reduced to 50% of maximum at the lines indicated therefor in the drawings, and being of substantially zero intensity at the boundary lines DB of FIG. 2 and therebeyond. It is of course understood that the lines UB at position B of FIG. 1 are indicative of the boundary lines of the beam when tilted upwardly as the mirror 12 rotates with the missile. Mirror 12, being slightly tilted or canted with respect to a plane perpendicular to the longitudinal axis of the rotating missile, reflects a microwave beam DB in a downward direction toward antenna 15 during the portion of a revolution of the missile when the mirror 12 is tilted downwardly thus producing a maximum intensity signal in a receiver forming a part of radar apparatus RA. When the rotating missile reaches the position along the trajectory C thereof indicated at B, the mirror 12 has rotated approximately and reflects the energy of beam M upwardly away from antenna 15, the reflected beam being indicated at UB,

thus to produce at apparatus RA a low intensity signal or possibly, no signal, as the case may be. Thus the reflected microwave signal varies from high intensity to low intensity during each revolution of the missile and reaches the peak or maximum condition at the same rotational position of the missile during each revolution.

The peaks or maximum, of the aforementioned signal received by radar apparatus RA, are passed to a rotational tracker RT by which the instantaneous rotational orientation of the steering charge ports 14 is made manifest at the command station D by interpolating between successive maxima of the received signal.

It is clear that the fire control system FC makes use of the signals indicative of the instantaneous position of the missile both rotational and along the trajectory as well as the position of the target to compute the proper time to fire the steering charge. At this time a signal is sent by command transmitter CT to a command receiver in the missile thereby to fire the steering charge 14 and change the course of the missile in order to intercept the target after a change in course thereof which may occur after the missile is launched.

It is, also, possible to use the command signal to detonate the explosive charge of the missile at the proper time, since the position of the missile with respect to the target is known, a coded signal being used for this purpose to distinguish from a signal from the command station to change course.

If several missiles are in the radar beam at the same time, one missile following the other in tandem fashion and therefore of different ranges, the radar circuits may be gated so that the positional information relating to each missile can be obtained separately and fed to the fire control computing system. In this manner one method of controlling missile traffic is possible. If several missiles are launched at the same instant and are in the radar beam at the same range, missile traific control hecomes more difficult. If, as aforesaid, the missiles are caused to rotate at different rates as by changing the angular setting of the fins, the output of the radar at the command station is analyzed so that the rotational position of each missile is obtained, If the missiles rotate at approximately the same speed when launched simultaneously, the mirrors may be altered prior to launching to provide the reflected beam of each of the missiles with a characteristic modulation, thereby to facilitate separation of the reflections at the command station.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. Apparatus for indicating the rotational orientation of a radar tracked rotating missile to a radar control station comprising a casing for said missile, and a radar mirror asymmetrically and rigidly mounted on the trailing end of said casing for rotation therewith thereby to continuously vary the intensity of the signal reflected therefrom and received by the radar control station.

2. Apparatus for determining the instantaneous rotational position thereof of a rotating missile having a steering charge comprising, in combination, a casing for said missile, an angularly mounted tail portion forming a radar mirror for said casing and rotating therewith, fixed means for transmitting a radar signal to said mirror and for receiving a reflection by the mirror of said signal at maximum intensity for a portion of each revolution of the missile, said reflection being directed toward said fixed means during a portion of each rotation of the missile.

3. Apparatus for determining the instantaneous rotational position of a body travelling along a trajectory comprising, in combination, angularly mounted reflecting means rotatable with said body and secured to the trailing end thereof, fixedly located transmitting means for transmitting a radar beam in a direction toward said reflecting means, and fixedly located receiving means for receiving a reflection of said beam from said reflecting means, said reflection of the beam being received at maximum intensity when the reflected beam is deflected downwardly during each revolution of the missile.

4. In a non-powered gun-launched rotating missile having a steering charge, a radar mirror mounted on the trailing end of said missile and rotating therewith, said mirror being tilted slightly with respect to the perpendicular to the axis of rotation of said missile, means for transmitting a radar beam in the direction of said mirror whereby said mirror reflects a portion of the radar beam, and means for receiving the reflected portion of said beam as the missile rotates whereby the reflected portion of the beam is received by said receiving means at maximum strength when the mirror is directed downwardly.

5. Apparatus for determining the rotational orientation of a rotating missile propelled from a gun and having a steering charge mounted therein comprising, in combination, a metallic casing for said missile, a metallic mirror angularly mounted in the trailing end of said missile and rotatable therewith, and a radar transmitter and receiver mounted adjacent said gun and adapted to transmit a signal to said mirror and to receive a reflection of said signal from said mirror, said reflected signal being received at maximum intensity when the mirror is tilted downwardly during a portion of each revolution of the missile and being received at minimum intensity when the mirror is tilted upwardly during another portion of each revolution of the missile.

6. Apparatus for determining the rotational orientation of a rotating missile propelled by a gun and having a steering charge mounted therein comprising, in combination, a casing for said missile having ports on one side thereof through which said steering charge is expended, a metallic radar mirror angularly mounted on the trailing end of said missile and rotatable therewith, a radar transmitter mounted adjacent said gun and adapted to transmit a microwave beam in a direction toward said mirror, a radar receiver mounted adjacent said gun and adapted to receive a reflection of said transmitted microwave signal from said mirror, the reflection of said signal being received by said receiver at maximum intensity when the mirror is tilted downwardly during a portion of each revolution of the missile and being received at minimum intensity when the mirror is tilted upwardly during another portion of each revolution, and rotational tracker means receiving the output of said radar receiver thereby to indicate the rotational position of the missile during the flight thereof.

7. In combination with a rotating missile, means for varying the amplitude of the reflections of a signal impinging on the missile as the same rotates comprising a reflector formed integral with the missile on the trailing and thereof for rotation therewith and disposed to angularly modify the signal reflections therefrom as the missile rotates whereby the amplitude of the signal reflections is varied.

8. In combination with a rotating missile of elongated configuration, a signal wave reflector securely affixed to the trailing end of said missile for rotation therewith and disposed at an angle in which the normal thereof is noncoincident with the longitudinal axis of the missile whereby a signal wave impinging thereon is asymmetrically reflected.

9. In a rotatable missile adapted to develop a characteristic indicative of the rotational orientation thereof from a wave signal impinging thereon while in flight comprising a casing for the missile, and a reflector affixed to the aft portion of said casing at the trailing end thereof, said reflector being configured to vary the angle of incidence of said impinging wave signal as the missile d rotates to thereby develop an asymmetrical characteristic indicative of the instantaneous rotational positions of the missile.

10. In a rotatable missile adapted to develop an asymmetrical characteristic indicative of the instantaneous rotational positions thereof from a Wave signal impinging thereon While in flight comprising a casing for the missile, and a Wave reflector formed integral with said casing at the trailing end thereof and angularly disposed with respect to the axis of said casing for modulating the reflections of the impinging wave signal as the missile rotates to thereby develop said asymmetrical characteristic.

11. In the missile of claim 10, said reflector being defined by a plane surface canted with respect to the normal of the longitudinal axis of the casing.

12. In a rotatable missile adapted to develop an asymmetrical characteristic indicative of the instantaneous rotational positions thereof from a wave signal impinging thereon while in flight comprising an elongated casing for 6 the missile, and a metallic Wave reflector formed integral in the trailing end of said casing and positioned at an angle with respect to a plane perpendicular to the longitudinal axis of the casing to vary the angle of reflection of said impinging Wave signal as the missile rotates thereby to develop said asymmetrical characteristic.

References Cited in the file of this patent UNITED STATES PATENTS 1,288,883 Harvey Dec. 24, 1918 2,212,110 Beuermann Aug. 20, 1940 2,405,597 Miller Aug. 13, 1946 2,432,984 Budenbom Dec. 23, 1947 2,443,643 Schelleng June 22, 1948 2,462,l02 Istvan Feb. 22, 1949 2,483,790 Stanko Oct. 4, 1949 2,557,949 De Loraine June 26, 1951 2,697,828 Heintz Dec. 21, 1954 

1. APPARATUS FOR INDICATING THE ROTATIONAL ORIENTATION OF A RADAR TRACKED ROTATING MISSILE TO A RADAR CONTROL STATION COMPRISING A CASING FOR SAID MISSILE, AND A RADAR MIRROR ASYMMETRICALLY AND RIGIDLY MOUNTED ON THE TRAILING END OF SAID CASING FOR ROTATION THEREWITH THEREBY TO CONTINUOUSLY VARY THE INTENSITY OF THE SIGNAL REFLECTED THEREFROM AND RECEIVED BY THE RADAR CONTROL STATION. 